Share 'Hang-ups to utilizing Manual J,D & S'

I'm looking for some insight into why HVAC contractors don't use the ACCA process for sizing and selecting HVAC and Distribution systems. I know part of it is the generational "I've done it this way for twenty years, and I'm not changing now" attitude, and some folks are apprehensive to anything related to a computer. But are there other factors that are at play that keep contractors from using t…